Process for making dibenzanthrone from the corresponding bz1.bz1&#39;-dibenzanthronyls



methods Patented Feb. 28, 1933 Uruiuao STATES A EN OFFI ARTHUR LI'iTTRINGI-IAUS OF MANNHEIM, nnmnion NERESHEIMEE, on LUDWIGS- mnn-on-rnn-nnmn, AND HANS Emma, or MANNHEIM, GERMANY, AS- sronons T0 GENERAL ANILINE wonxs, mo, or NEW onx, N. Y., A consona- TION OF DELAWARE IROCE SS FOR MAKING DIBENZANTHRONE FROM THE CORRESPONDTN G BZLBZI' A DIBENZANTHRONYLS a No Drawing. Application filed December 9, 1926, Serial No. 153,725, and'in Germany December We have now found that Bz1.Bz1'-dibenzanthronyls of which the unsubstituted Bz1.Bzl dibenzanthronyl corresponds to the formula stufis'of the benzanthrone series with a good, and in some cases almost a quantitative yield, by treatment With alkaline condensing agents. The formation ofthe dyestufi proceeds Without difliculty and at comparatively 7 low temperatures. In some cases it is advisable to add a reducing agent, for instance formaldehyde-sulfoxylate to the alkaline condensing agent. Then the formation of 25 the dyestufl sometimes takes place in aqueous suspension and at temperatures slightly exceeding 100 C.

The BZLBZl-dibenzanthronyls employed as initial materials according to the present invention can be prepared for example by treating B21 -halogenbenzanthrones with metal powders, or by boiling Bz1-diazoben zanthrones in the presence of cuprous chloride, or by the oxidation of benzanthrones in acid solution according to the process of the German Patent 431,774.

According to the present invention derivatives of dibenzanthrone may also be prepared, Which are not obtainable, or only in an impure state, by theusual and previously known methods. Thus, for example by fusing halogen-Bz1 .Bz1-dibenzanthronyls with alcoholic caustic potash, under the particularly mild conditions employed according to this invention, the corresponding halogendibenzanthrones are readily obtained. If, on the other hand, it is attempted to produce the same dyestuffs by applying the previously known and usual 7 alkaline condensation to halogen-containing benzanthrones or 2.2-dibenzanthronyls, dyestuffs of different shades, and mostly with a substantially inferior yield, are obtained.

The following examples will further illusout in practice but the invention is not limited to these examples. The parts are by weight. Ewample 1 10 parts of Bz1.Bz1-dibenzanthronyl are introduced in about half an hour into a melt of 100 parts of caustic potash and parts of ethyl alcohol heated to from 120 to 130 centigrade; The formation of dibenzanthrone of the formula sets in almost immediately, accompanied by a little eifervescing." Stirring is continued for a further 2 hours at a temperature of from 120 to 130 centigrade, whereupon the caustic soda solution (40 Baum strength) and 3000 parts of water is heated to bOlllIlg,

- trate how the said invention may be carried under a reflux condenser, for about 12 hours, in the course of which period it is treated with an addition of 60 parts ofisodium ,forma'ldehydesulfoxylatefij The violet-red vat of the 5 dyestuif is filtered. after addition of caustic soda solution and sodium hydrosulfite, if re-' quired, and the dyestufl is precipitated, preferably by oxidizing agents such as sodium 'hypochloritesolution; a

Example 3 If the Bz1.Bzl'-dibenzanthronyl in EX ample 1 be replaced by Bz2.Bz2-dimethyl BzLBzl -dibenzanthronyl corresponding to the formula o o a he (obtainable in accordance with the German Patent 431,774 bythe oxidation of 3Z2- methylbenzanthrone, and forming a brown powder, furnishing a bluish-red solution, without appreciable fluorescence, in concentrated sulfuric acid), there will be obtained, 7 after a short reaction, a deep blue melt from which B22322-dimethyl-dibenzanthrone of the formula =5 canbe recovered by treatment inthe usual manner. The crude dyestufl' can be purified by re-solution' from organic solvents. 'It forms a dark blue powder, with a bronze sheen, and is soluble with comparative ease in organic liquids of low'boiling point, such as acetone, or benzene, and far more readily in media of high boiling point such as trichlorbenzene or nitrobenzene, the solution 55 being of a brilliant red-violet color and exhibiting an intense red fluorescence. The solution in concentrated sulfuric acid is also red-violet in color. From a blue vat, the dye stuff gives blue-violet dyeings on cotton, and these differ from those produced by dibenzanthrone by greater brightness and the valuable property of not displaying any appreciable tendency to increased redness of tinge when moistened with water;

7 7 5 Example 4 A solution'or suspension of 10 parts of 6.6-dichlor-Bz1.Bz1-dibenzanthronyl correspondingto the formula (an olive-green powder repared by the oxidation of fi-chlorbenzant mm, and dissolving in concentrated sulfuric acid to a carmine solution with red fluorescence), 50 parts of caustic potash, and parts'of aniline, is heated to a temperature of to C. for about an hour. The crude dyestuif obtained after the removal ofthe aniline may be purified, forexample, byvextraction with acetone. .The dyestuff of-the formula forms a blackish powder, which is soluble with difliculty in organic solvents but readily so (to a red-violet solution) in concentrated sulfuric acid. It dyes cotton, from a redviolet vat, shades which are of substantially greener tinge than those produced by dibenzanthrone. p

, i The same dyestuif is obtained by treating 6,6 dichlor-BzLBzl-dibenzanthronyl with alcoholic caustic potash as in Example 1. On

the other hand, the dyestufl obtainable in the 7 known manner from 6-chlorbenzanthrone under the same conditions gives weaker and redder dyeings.

We claim: r

1. The process of producing vat dyestuffs of the dibenzanthrone series which comprises treating a Bz1.Bz1-dibenzanthronyl with an alkaline condensing agent at a temperature above 100 C. and up to about 135 C.

2. The process of producing diben zan throne which comprises treating Bz1.Bz1'- dibenzanthronyl with an alkaline condensing agent at a temperature above 100 C. and up to about 135 C.

In testimony whereof We have hereunto set our hands.

ARTHUR LT lTTRINGHAUS.

HEINRICH NERESHEIMER. HANS EMMER. 

